In an RF receiver, an RF filter is generally used between an antenna and a low noise amplifier (LNA). The RF filter performs a function of a band pass filter (BPF) which passes signals of desired bands among a diverse range of channels, and filters signals of undesired bands. Such an RF filter may be difficult to integrate into a single chip. Where the RF filter is implemented on a chip, the performance of the RF filter degrades, and accordingly, the RF filter is typically implemented using an external element such as a surface acoustic wave (SAW) filter.
FIG. 1 illustrates an apparatus for removing interference signals in a conventional RF receiver. As illustrated in FIG. 1, the conventional interference signal removing apparatus includes an antenna 10, an RF SAW filter 20, and a LNA 30. Where RF signals are transmitted to the antenna 10 through a channel, the RF SAW filter 20 performs band pass filtering and the on-chip LNA 30 of the RF receiver suppresses noise and amplifies desired signals.
The RF SAW filter 20 is an external element and it is not integrated into a single chip. It is also necessarily provided with an external SAW filter for each desired band in order to selectively receive the desired band among a multi-band, so the cost and size of the SAW filter may increase.